Multi-terminal cross-point synaptic device using nanocrystal dot structures

Abstract

Described herein is a crossbar array that includes a cross-point synaptic device at each of a plurality of crosspoints. The cross-point synaptic device includes a weight storage element comprising a set of nanocrystal dots. Further, the cross-point synaptic device includes at least three terminals for interacting with the weight storage element, wherein a weight is stored in the weight storage element by sending a first electric pulse via a gate terminal from the at least three terminals, the first electric pulse causes the nanocrystal dots to store a corresponding charge, and the weight is erased from the weight storage element by sending a second electric pulse via the gate terminal, the second electric pulse having an opposite polarity of the first electric pulse.

What is claimed is: 
     
       1. A crossbar array comprising:
 a cross-point synaptic device at each of a plurality of crosspoints, the cross-point synaptic device comprising:
 a weight storage element comprising a set of nanocrystal dots; and 
 at least three terminals for interacting with the weight storage element, wherein a weight is stored in the weight storage element by sending a first electric pulse via a gate terminal from the at least three terminals, the first electric pulse causes the nanocrystal dots to store a corresponding charge, and the weight is erased from the weight storage element by sending a second electric pulse via the gate terminal, the second electric pulse having an opposite polarity of the first electric pulse, wherein the nanocrystal dots have a uniformly varying size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material. 
 
 
     
     
       2. The crossbar array of  claim 1 , wherein the nanocrystal dots have a decreasing size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material. 
     
     
       3. The crossbar array of  claim 1 , wherein the nanocrystal dots have an increasing size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material. 
     
     
       4. The crossbar array of  claim 1 , wherein the nanocrystal dots have one of a round shape, a half-moon shape, and a square shape. 
     
     
       5. The crossbar array of  claim 1 , wherein the nanocrystal dots are in a single layer in the gate terminal. 
     
     
       6. The crossbar array of  claim 1 , wherein the nanocrystal dots are stacked in multiple layers in the gate terminal. 
     
     
       7. A system comprising:
 a controller; and 
 a crossbar array coupled with the controller, the crossbar array configured to operate as a neural network, the crossbar array comprising:
 a cross-point synaptic device at each of a plurality of crosspoints, the cross-point synaptic device comprising:
 a weight storage element comprising a set of nanocrystal dots; and 
 at least three terminals for interacting with the weight storage element, wherein a weight is stored in the weight storage element by sending a first electric pulse via a gate terminal from the at least three terminals, the first electric pulse causes the nanocrystal dots to store a corresponding charge, and the weight is erased from the weight storage element by sending a second electric pulse via the gate terminal, the second electric pulse having an opposite polarity of the first electric pulse, wherein the nanocrystal dots have a uniformly varying size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material. 
 
 
 
     
     
       8. The system of  claim 7 , wherein the nanocrystal dots have an increasing size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material. 
     
     
       9. The system of  claim 7 , wherein the nanocrystal dots have a decreasing size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material. 
     
     
       10. The system of  claim 7 , wherein the nanocrystal dots have one of a round shape, a half-moon shape, and a square shape. 
     
     
       11. The system of  claim 7 , wherein the nanocrystal dots are in a single layer in the gate terminal. 
     
     
       12. The system of  claim 7 , wherein the nanocrystal dots are stacked in multiple layers in the gate terminal. 
     
     
       13. A method for controlling weight stored in a crossbar array used for implementing a neural network, the method comprising:
 updating a weight stored by a weight storage element of a cross-point synaptic device at each of a plurality of crosspoints of the crossbar array by sending a first electric pulse via a gate terminal of the weight storage element, the first electric pulse causes a set of nanocrystal dots in the gate terminal to store a corresponding charge representing the weight, wherein the nanocrystal dots have a uniformly varying size from a drain terminal to a source terminal from the at least three terminals, the size controlled by temperature when growing the nanocrystal dots in a dielectric material; and 
 erasing the weight stored in the weight storage element by sending a second electric pulse via the gate terminal, the second electric pulse having an opposite polarity of the first electric pulse. 
 
     
     
       14. The method of  claim 13 , wherein the nanocrystal dots have an increasing size from a first terminal to a second terminal of the weight storage element, the size controlled by temperature when growing the nanocrystal dots in a dielectric material. 
     
     
       15. The method of  claim 13 , wherein the nanocrystal dots have one of a round shape, a half-moon shape, and a square shape. 
     
     
       16. The method of  claim 13 , wherein the nanocrystal dots are in a single layer in the gate terminal. 
     
     
       17. The method of  claim 13 , wherein the nanocrystal dots are stacked in multiple layers in the gate terminal.